Blockade of central cholinergic receptors impairs new learning and increases proactive interference in a word paired-associate memory task.

Experimental data and computational models suggest that blockade of muscarinic cholinergic receptors impairs paired-associate learning and increases proactive interference (E. DeRosa & M. E. Hasselmo, 2000; M. E. Hasselmo & J. M. Bower, 1993). The results presented here provide evidence in humans supporting these hypotheses. Young healthy subjects first learned baseline word pairs (A-B) and, after a delay, learned additional overlapping (A-C) and nonoverlapping (D-E) word pairs. As predicted, when compared with subjects who received the active placebo glycopyrrolate (4 microg/kg) and subjects who were not injected, those who received scopolamine (8 microg/kg) showed (a) overall impairment in new word paired-associate learning, but no impairment in cued recall of previously learned associates; and (b) greater impairment in learning overlapping (A-C) compared with nonoverlapping (D-E) paired associates.

Influenza burden of illness: estimates from a national prospective survey of household contacts in France.

BACKGROUND: The burden of influenza among ambulatory patients is still relatively unknown, although this knowledge is crucial for evaluating strategies against influenza. We estimated the impact of influenza in terms of uncomplicated morbidity and its consequences on health care utilization and lost workdays. METHODS: A national prospective household contact study between January 4, 2000, and March 15, 2000, in France recruited the households of 946 persons who visited a physician (index cases); 395 households with influenza-positive index cases completed the follow-up, which assessed the clinical impact of influenza, medical visits, treatment, and lost workdays in these index cases and their contacts. RESULTS: Of 817 assessable household contacts, 313 developed clinical influenza (secondary cases); 178 (57%) of them visited a physician at least once (consulting secondary cases). The median duration of illness was 8 days (95% confidence interval [CI], 7-8 days) in index cases, 7 days (95% CI, 7-8 days) in consulting secondary cases, and 4 days (95% CI, 3-5 days) in nonconsulting secondary cases (P<.001); the median duration of treatment in these groups was 8 days (95% CI, 8-9 days), 8 days (95% CI, 7-10 days), and 5 days (95% CI, 4-6 days), respectively (P<.001); and their mean +/- SD number of lost workdays was 4.0 +/- 2.8, 2.9 +/- 2.5, and 0.3 +/- 0.6, respectively, in working adults (P<.001). CONCLUSIONS: These results confirm the substantial burden of illness of influenza. The results should be useful for evaluating the cost-effectiveness of strategies against influenza.